1. Field of the Invention
This invention relates to apparatus for applying agricultural chemicals including particularly minimal-contact-kill type herbicides, either alone or in conjunction with the simultaneous application of another agricultural chemical such as a sprayable insecticide, fertilizer or other herbicide.
A primary object and accomplishment of the invention is to provide apparatus for applying minimal-contact-kill type herbicides to the portions of weeds, field grasses, volunteer growth or other undesired plants extending above the tops of a field crop without such herbicides contacting and killing portions of the field crop with which the undesired plants to be killed are interspersed. A second, very significant object and accomplishment of the invention is to provide apparatus not only satisfying the noted primary object, but also incorporating practical means in compatible combination with the contact applicator means for applying a spray type agricultural chemical during a single pass through a field, when desired. Other important objects and advantages of the invention will be pointed out in or become apparent from the disclosure and claims which follow.
Agricultural chemicals can be categorized in various ways, such as with respect to their purpose (e.g., herbicides, fertilizers, insecticides, etc.), their generality in significantly affecting a large variety of types of plants or specificity in primarily affecting only a single or small number of types of plants, their physical nature when applied (e.g., liquid, powdered, etc.), their mode of operative introduction to plants being treated (e.g., by absorption through foliage, by absorption through roots, etc.), their characteristics concerning the amount required for effective action, and their mode of optimal field application (e.g., direct engagement of foliage of plants by wetted carrier, liquid spraying upon foliage of plants and/or adjacent soil, spreading of powder upon foliage of plants and/or adjacent soil, tilling into soil, etc.). The apparatus of this invention permits the effective application of relatively small quantities of agricultural chemicals (especially herbicides of the minimal-contact-kill type), in liquid form and of nature to affect virtually any plants contacted thereby, by moving a carrier wetted with such chemical into direct contact with an upper portion of the foliage of plants to be killed or otherwise treated by the contact-acting chemical, and also permits the simultaneous application to adjacent plants and/or soil of any other desired type of agricultural chemical in liquid form, by liquid spraying, in order that two agricultural chemicals for different purposes may be applied during a single pass over a given field area.
2. Description of the Prior Art
With respect to the primary capability of the apparatus of this invention for applying a minimal-contact-kill type herbicide or the like, the closest known prior art are so-called "ropewick applicators", which are generally described in "Is Your Ropewick Really Wicking?", by Dale Bruce of the Extension Information department of Iowa State University, published in the July 10, 1982 issue of Wallaces Farmer, and of which a typical example is the ropewick applicator offered by Monsanto Company for use in applying its widely advertised minimal-contact-kill type liquid form herbicide sold under the trademark "Roundup". Such ropewick applicators essentially involve an elongate, hollow container adapted to be mounted on a tractor in laterally extending relationship to the path of travel of the latter, which can be filled with a quantity of the liquid herbicide material and is provided with spaced pairs of holes along its undersurface, each pair of which holes receives an end portion of a generally U-shaped, depending loop of rope of nylon or other material capable of functioning as a wettable "wick"; the herbicide material flows by gravity into the interstices between the strands of each rope loop, and the container is set at a height such that, as the tractor traverses a field, the wetted loops will directly engage an upper portion of the foliage of field weeds, volunteer corn or the like to be killed at a level above the tops of any field crop also growing in the same field and will through that engagement deposit a small but sufficient amount of the herbicide upon the foliage of the weeds or the like to kill the same.
Such ropewick applicators and minimal-contact-kill type herbicides have proved quite effective in killing weeds or the like contacted thereby. However, such ropewick type applicators suffer from the serious disadvantage that the liquid herbicide material inherently tends to accumulate at and drip from the lower bight portion of the rope loops, with devastating effect upon a crop growing in the field being treated by virtue of the generality of the killing action of such herbicides upon virtually any plant life that may be contacted by even a miniscule quantity thereof. As pointed out in the mentioned publication, ropewick applicators have also been found subject to a number of other limitations and disadvantages, including the difficulty of achieving a proper rate of gravity flow of the herbicide material into the rope loops.
With respect to the secondary capability of the apparatus of this invention for efficiently permitting the simultaneous application of a second, liquid, agricultural chemical of virtually any type by spraying, the general technique of applying such a material by spraying, either from an airplane or from a ground-based device for that specific purpose, is, of course, well known and common practice. However, insofar as I am aware, no prior apparatus has ever provided for the coordinated and simultaneous application of both a direct foliage engagement type agricultural chemical and a sprayed type agricultural chemical during a single pass through the field area and in manner in which the application parameters are appropriate for both materials and can be jointly accommodated to plant height, terrain conditions and the like.